Gas Holdup, Axial Dispersion, and Mass Transfer Studies in Bubble Columns

Abstract

This article presents an extensive study on the gas holdup, axial liquid dispersion, and mass transfer for packed, trayed, and empty bubble columns. Four types of structured packings (Super-Pak, Flexipac, Mellapak, and Gauze) and two types of perforated partition trays (with 25% and 40% tray open area) were used to characterize the packed and trayed bubble columns, respectively. It was observed that the gas holdup and mass transfer characteristics of the packed and trayed bubble columns are superior to those of an empty bubble column, while the axial dispersion coefficients are much lower. This article discusses in detail the effect of the liquid and gas flow rates, liquid-phase viscosity, and type of internals. Additionally, experimental data of the packed, trayed, and empty bubble column are correlated by dimensionless numbers. Novel empirical correlations are proposed for the gas holdup, Bodenstein number (for the axial dispersion coefficient), and Stanton number (for the volumetric mass transfer coefficient), as a function of the Froude and Galileo dimensionless numbers.